T-lymphocyte subpopulations in tuberculosis

BACKGROUND

Tuberculosis is associated with both qualitative and quantitative defects in the cell mediated immune response. The changes that occur in the lymphocyte profile in blood in children with tuberculosis are not well understood.

DESIGN

Prospective study.

SETTING

Referral hospitals.

METHODS

Lymphocyte subpopulations were determined by flow cytometry in 17 healthy tuberculin positive children, in 22 children with newly diagnosed pulmonary tuberculosis and in 8 of these children after antituberculosis therapy.

RESULTS

Absolute numbers and percentages of CD3+ and CD4+ T cells were reduced in children with tuberculosis, compared to controls. CD4+ counts increased significantly following antituberculosis treatment, compared to baseline values. In contrast, the proportion of T cells expressing the gdT cell receptor was similar in tuberculosis patients and controls.

CONCLUSION

Children with tuberculosis have a systemic decrease in the proportion and number of CD3+ and CD4+ T cells which reverses during therapy.

Synthesis of allysine ethylene acetal using phenylalanine dehydrogenase from Thermoactinomyces intermedius

Allysine ethylene acetal [(S)-2-amino-5-(1,3-dioxolan-2-yl)-pentanoic acid (2)] was prepared from the corresponding keto acid by reductive amination using phenylalanine dehydrogenase (PDH) from Thermoactinomyces intermedius ATCC 33205. Glutamate, alanine, and leucine dehydrogenases, and PDH from Sporosarcina species (listed in order of increasing effectiveness) also gave the desired amino acid but were less effective. The reaction requires ammonia and NADH. NAD produced during the reaction was recyled to NADH by the oxidation of formate to CO(2) using formate dehydrogenase (FDH). PDH was produced by growth of T. intermedius ATCC 33205 or by growth of recombinant Escherichia coli or Pichia pastoris expressing the Thermoactinomyces enzyme. Using heat-dried T. intermedius as a source of PDH and heat-dried Candida boidinii SC13822 as a source of FDH,98%, but production of T. intermedius could not be scaled up. Using heat-dried recombinant E. coli as a source of PDH and heat-dried Candida boidinii 98%. In a third generation process, heat-dried methanol-grown P. pastoris expressing endogenous FDH and recombinant Thermoactinomyces98% ee.

Treatment of tuberculosis

Early diagnosis and prompt treatment of tuberculosis is important in order to minimise complications and sequelae. It is important to select the proper regimen and ensure that the patient is getting adequate number of drugs for adequate duration. The principles of short course chemotherapy and the rationale behind the currently recommended regimens are outlined in this article. Standard (daily or intermittent) 6-month short course regimens are sufficient to cure most forms of tuberculosis in children and only severe forms like miliary, meningitis and neurotuberculosis require a longer duration of treatment. Worldwide, the DOTS strategy is now recommended in order to ensure cure and cut down the transmission of disease in the community and wherever possible, should be employed in the treatment of tuberculosis in children also.

The human herpesvirus 8 homolog of Epstein-Barr virus SM protein (KS-SM) is a posttranscriptional activator of gene expression

Homologs of the Epstein-Barr virus (EBV) SM protein exist in several human and nonhuman herpesviruses. Structure and function differ significantly among these proteins. We have cloned and characterized the human herpesvirus 8 (HHV8) gene, KS-SM, which is homologous to the EBV SM and herpes simplex virus ICP27 genes, from an HHV8-infected primary effusion lymphoma. KS-SM is shown to be a posttranscriptional activator of gene expression in cotransfection studies. KS-SM activated gene expression in a gene-specific, promoter-independent manner. In particular, KS-SM enhanced the expression of KDR/flk-1, a receptor for vascular endothelial growth factor (VEGF), in cotransfection studies. Since expression of KDR/flk-1 is increased in Kaposi's sarcoma and HHV8-infected cell cultures and VEGF enhances the proliferation of HHV8-infected cells, KS-SM may play a pathogenic role in Kaposi's sarcoma.

First report of tropical myositis and crescentic glomerulonephritis in a renal transplant recipient

We describe a renal transplant recipient who presented with tropical myositis and acute allograft dysfunction 2(1/2) years after transplantation. Graft biopsy showed immune-complex crescentic glomerulonephritis. He was receiving only 7.5 mg/d of prednisolone for more than 2 months before presentation. Renal function did not improve despite treatment with antibiotics, methylprednisolone pulse therapy, and cyclophosphamide. He died of septicemia.

Sero diagnosis of tuberculosis in children using two ELISA kits

The diagnosis of childhood tuberculosis is based on circumstantial evidence in the absence of a gold standard in the majority of cases. Sero-diagnosis offers scope for an early diagnosis in a variety of clinical conditions and is simple to perform. A number of mycobacterial antigens have been used for antibody detection assays and several are available as kits in the market. This study was done to evaluate the value of antibody detection kits (ELISA) against the A60 antigen and 38 kDa antigen of Mycobacterium tuberculosis in the diagnosis of childhood tuberculosis at the outpatient department of the Institute of Social Paediatrics, Government Stanley Hospital in collaboration with Tuberculosis Research Centre, Chennai. Thirty five children with pulmonary tuberculosis, 7 with TB lymphadenitis and 22 healthy controls were studied. In addition to routine investigations including gastric lavage for AFB culture, serum antibodies against the A60 and 38 kDa antigens were assayed using commercially available ELISA kits. With A60, IgM serum levels were positive in 74% of pulmonary TB cases, 57% of TB lymphadenitis cases and 50% of controls. A60 IgG was positive in 17% of pulmonary TB, 86% of TB lymphadenitis and 14% of controls. The 38 kDa IgG antibody was positive in 37% of pulmonary and 86% of TB lymphadenitis cases and 27% of controls. Among 10 culture confirmed cases, A60 IgM was positive in 8, A60 IgG in 3 and 38 kDa IgG in 5 patients. The sensitivity of the tests ranged between 29% and 71% and specificity between 50% and 86%. Although the numbers are small, the results suggest that serodiagnosis using the currently available antigens of M. tuberculosis is unlikely to be a confirmatory test for tuberculosis in children.

Pulmonary function testing in office practice

With the wide availability of simple to operate pulmonary function equipment, these tests can now be performed in the office or clinic setting. The use of pulmonary function tests in the assessment of patients with pulmonary diseases has thus expanded. These simple tests rely on data generated from a forced expiratory vital capacity maneuver which can be performed reliably by most children over the age of 6 or 7 years. Pulmonary function tests provide both diagnostic and prognostic information and help in the management of a number of respiratory diseases. The number of tests available vary with the level of sophistication of the pulmonary function laboratory; in most situations simple spirometry is adequate. Several new and inexpensive peak flow meters are now available for home use; these are very useful for home monitoring of asthma patients. Physicians caring for patients with asthma or other chronic respiratory diseases should be encouraged to use these tests routinely in the management of these children.

Structural genomics: beyond the human genome project

With access to whole genome sequences for various organisms and imminent completion of the Human Genome Project, the entire process of discovery in molecular and cellular biology is poised to change. Massively parallel measurement strategies promise to revolutionize how we study and ultimately understand the complex biochemical circuitry responsible for controlling normal development, physiologic homeostasis and disease processes. This information explosion is also providing the foundation for an important new initiative in structural biology. We are about to embark on a program of high-throughput X-ray crystallography aimed at developing a comprehensive mechanistic understanding of normal and abnormal human and microbial physiology at the molecular level. We present the rationale for creation of a structural genomics initiative, recount the efforts of ongoing structural genomics pilot studies, and detail the lofty goals, technical challenges and pitfalls facing structural biologists.

The Saccharomyces cerevisiae ubiquitin-proteasome system

Our studies of the yeast ubiquitin-proteasome pathway have uncovered a number of general principles that govern substrate selectivity and proteolysis in this complex system. Much of the work has focused on the destruction of a yeast transcription factor, MAT alpha 2. The alpha 2 protein is polyubiquitinated and rapidly degraded in alpha-haploid cells. One pathway of proteolytic targeting, which depends on two distinct endoplasmic reticulum-localized ubiquitin-conjugating enzymes, recognizes the hydrophobic face of an amphipathic helix in alpha 2. Interestingly, degradation of alpha 2 is blocked in a/alpha-diploid cells by heterodimer formation between the alpha 2 and a1 homeodomain proteins. The data suggest that degradation signals may overlap protein-protein interaction surfaces, allowing a straightforward steric mechanism for regulated degradation. Analysis of alpha 2 degradation led to the identification of both 20S and 26S proteasome subunits, and several key features of proteasome assembly and active-site formation were subsequently uncovered. Finally, it has become clear that protein (poly) ubiquitination is highly dynamic in vivo, and our studies of yeast de-ubiquitinating enzymes illustrate how such enzymes can facilitate the proteolysis of diverse substrates.

The Doa4 deubiquitinating enzyme is required for ubiquitin homeostasis in yeast

Attachment of ubiquitin to cellular proteins frequently targets them to the 26S proteasome for degradation. In addition, ubiquitination of cell surface proteins stimulates their endocytosis and eventual degradation in the vacuole or lysosome. In the yeast Saccharomyces cerevisiae, ubiquitin is a long-lived protein, so it must be efficiently recycled from the proteolytic intermediates to which it becomes linked. We identified previously a yeast deubiquitinating enzyme, Doa4, that plays a central role in ubiquitin-dependent proteolysis by the proteasome. Biochemical and genetic data suggest that Doa4 action is closely linked to that of the proteasome. Here we provide evidence that Doa4 is required for recycling ubiquitin from ubiquitinated substrates targeted to the proteasome and, surprisingly, to the vacuole as well. In the doa4Delta mutant, ubiquitin is strongly depleted under certain conditions, most notably as cells approach stationary phase. Ubiquitin depletion precedes a striking loss of cell viability in stationary phase doa4Delta cells. This loss of viability and several other defects of doa4Delta cells are rescued by provision of additional ubiquitin. Ubiquitin becomes depleted in the mutant because it is degraded much more rapidly than in wild-type cells. Aberrant ubiquitin degradation can be partially suppressed by mutation of the proteasome or by inactivation of vacuolar proteolysis or endocytosis. We propose that Doa4 helps recycle ubiquitin from both proteasome-bound ubiquitinated intermediates and membrane proteins destined for destruction in the vacuole.

Association with the cellular export receptor CRM 1 mediates function and intracellular localization of Epstein-Barr virus SM protein, a regulator of gene expression

Splicing and posttranscriptional processing of eukaryotic gene transcripts are linked to their nuclear export and cytoplasmic expression. Unspliced pre-mRNAs and intronless transcripts are thus inherently poorly expressed. Nevertheless, human and animal viruses encode essential genes as single open reading frames or in the intervening sequences of other genes. Many retroviruses have evolved mechanisms to facilitate nuclear export of their unspliced mRNAs. For example, the human immunodeficiency virus RNA-binding protein Rev associates with the soluble cellular export receptor CRM 1 (exportin 1), which mediates nucleocytoplasmic translocation of Rev-HIV RNA complexes through the nuclear pore. The transforming human herpesvirus Epstein-Barr virus (EBV) expresses a nuclear protein, SM, early in its lytic cycle; SM binds RNA and posttranscriptionally activates expression of certain intronless lytic EBV genes. Here we show that both the trans-activation function and cytoplasmic translocation of SM are dependent on association with CRM 1 in vivo. SM is also shown to be associated in vivo with other components of the CRM 1 export pathway, including the small GTPase Ran and the nucleoporin CAN/Nup214. SM is shown to be present in the cytoplasm, nucleoplasm, and nuclear envelope of transfected cells. Mutation of a leucine-rich region (LRR) of SM inhibited CRM 1-mediated cytoplasmic translocation and SM activity, as did leptomycin B, an inhibitor of CRM 1 complex formation. Surprisingly, however, leptomycin B treatment and mutation of the LRR both led to SM becoming more tightly attached to intranuclear structures. These findings suggest a model in which SM is not merely a soluble carrier protein for RNA but rather is bound directly to intranuclear proteins, possibly including the nuclear pore complex.

p300/cAMP-responsive element-binding protein interactions with ets-1 and ets-2 in the transcriptional activation of the human stromelysin promoter

In this paper we show that transcription factors Ets-1 and Ets-2 recruit transcription adapter proteins p300 and CBP (cAMP-responsive element-binding protein) during the transcriptional activation of the human stromelysin promoter, which contains palindromic Ets-binding sites. Ets-2 and p300/CBP exist as a complex in vivo. Two regions of p300/CBP between amino acids (a.a.) 328 and 596 and a. a. 1678 and 2370 independently can interact with Ets-1 and Ets-2 in vitro and in vivo. Both these regions of p300/CBP bind to the transactivation domain of Ets-2, whereas the C-terminal region binds only to the DNA binding domain of Ets-2. The N- and the C-terminal regions of CBP (a.a. 1-1097 and 1678-2442, respectively) which lack histone acetylation activity independently are capable of coactivating Ets-2. Other Ets family transcription factors failed to cooperate with p300/CBP in stimulating the stromelysin promoter. The LXXLL sequence, reported to be important in receptor-coactivator interactions, does not appear to play a role in the interaction of Ets-2 with p300/CBP. Previous studies have shown that the stimulation of transcriptional activation activity of Ets-2 requires phosphorylation of threonine 72 by the Ras/mitogen-activated protein kinase signaling pathway. We show that mutation of this site does not affect its capacity to bind to and to cooperate with p300/CBP.

Cytokine production in children with tuberculous infection and disease

To determine if the manifestations of initial infection with Mycobacterium tuberculosis reflect changes in the balance of T cell cytokines, we evaluated cytokine production by M. tuberculosis-stimulated peripheral blood mononuclear cells (PBMCs) from 24 children with tuberculosis and 22 children who were healthy tuberculin reactors. PBMCs from patients with tuberculosis had lower production and mRNA expression of interferon gamma (IFN-gamma) than did PBMCs from healthy tuberculin reactors. IFN-gamma production was most severely depressed in patients with moderately advanced and far-advanced pulmonary disease and in malnourished patients. Production of IL-12, IL-4, and IL-10 was similar in tuberculosis patients and healthy tuberculin reactors. These results indicate that, during the initial immune response to M. tuberculosis, development of tuberculosis is associated with diminished IFN-gamma production, which is not due to reduced production of IL-12 or enhanced production of IL-4 or IL-10.

Adenovirus-mediated tissue-targeted expression of the HSVtk gene for the treatment of breast cancer

In an effort to develop a genetic therapy for the treatment of breast cancer, we constructed adenoviral vectors containing either the beta-galactosidase (beta-gal) reporter gene or the herpes simplex thymidine kinase (HSVtk) suicide gene driven by breast tissue-specific promoters. We utilized upstream regulatory sequences from either the human alpha-lactalbumin (hALA) gene, or the ovine beta-lactoglobulin (oBLG) gene in these vector constructs to target expression of heterologous genes transcriptionally to breast cancer cells both in vitro and in vivo. Data derived from breast tissue-specific reporter vectors in vitro demonstrate that expression from the hALA and oBLG promoters are indeed specific for breast cells (T47D, MCF-7, ZR75-1) when compared with non-breast cells (U2OS, HeLa). Moreover, these vectors displayed tumor cell specificity when compared with the normal MCF-10A breast cell line. These vectors also displayed breast tissue specificity when injected systemically (i.v.) into lactating Balb/c mice, which suggests that these promoters maintain their tissue-specific expression pattern within the context of the adenoviral genome in vivo. Tumors, derived from T47D human breast cancer cells, were established in nude mice and injected with either the tissue-specific reporter or suicide vectors. Results from tumors injected (i.t.) with reporter adenoviruses demonstrate that these promoters are active in T47D cells when grown as established tumors and we observed a marked regression of tumors injected with suicide vectors and treated systemically with gancyclovir (150 mg/kg/day) when compared with control animals. Moreover, mouse survival was prolonged after 35 days in mice undergoing therapy with the suicide vectors in conjunction with gancyclovir when compared with the control animals. These data suggest that the transcriptionally targeted hALA or oBLG driven expression of the HSVtk gene may be a feasible therapy for the treatment of human breast cancer.

Enterococcus avium endocarditis in an infant with tetralogy of Fallot

We report a case of infective endocarditis secondary to Enterococcus avium in a 1-year-old infant with tetralogy of Fallot and a Blalock-Taussig shunt. To our knowledge, this is the first case of E. avium endocarditis to be reported.

Affinity purification of recombinant interferon-alpha on a mimetic ligand adsorbent

A method for improved refolding and purification of recombinant human interferon-alpha (rh-IFN-alpha) from inclusion bodies is described. The optimal conditions of refolding were obtained by the addition of 0.5 M l-arginine to the refolding buffer. The rh-IFN-alpha was purified to near homogeneity utilizing a single-step chromatography on a mimetic dye-ligand matrix. Improved refolding, coupled to a single-column affinity purification strategy, resulted in a 10-fold increase in the yield of rh-IFN-alpha. This single-step purification protocol yielded approximately 50 mg of purified rh-IFN-alpha from 1 liter of shake flask culture. The rh-IFN-alpha prepared by this protocol was found to be essentially monomeric based on HPLC gel filtration and nonreducing SDS-PAGE. It had a specific activity of approximately 2.8 x 10(8) IU/mg, measured as inhibition of cytopathic effect of encephalomyocarditis virus on A549 human lung carcinoma cells.

Transcriptional activation signals found in the Epstein-Barr virus (EBV) latency C promoter are conserved in the latency C promoter sequences from baboon and Rhesus monkey EBV-like lymphocryptoviruses (cercopithicine herpesviruses 12 and 15)

The Epstein-Barr virus (EBV) EBNA2 protein is a transcriptional activator that controls viral latent gene expression and is essential for EBV-driven B-cell immortalization. EBNA2 is expressed from the viral C promoter (Cp) and regulates its own expression by activating Cp through interaction with the cellular DNA binding protein CBF1. Through regulation of Cp and EBNA2 expression, EBV controls the pattern of latent protein expression and the type of latency established. To gain further insight into the important regulatory elements that modulate Cp usage, we isolated and sequenced the Cp regions corresponding to nucleotides 10251 to 11479 of the EBV genome (-1079 to +144 relative to the transcription initiation site) from the EBV-like lymphocryptoviruses found in baboons (herpesvirus papio; HVP) and Rhesus macaques (RhEBV). Sequence comparison of the approximately 1,230-bp Cp regions from these primate viruses revealed that EBV and HVP Cp sequences are 64% conserved, EBV and RhEBV Cp sequences are 66% conserved, and HVP and RhEBV Cp sequences are 65% conserved relative to each other. Approximately 50% of the residues are conserved among all three sequences, yet all three viruses have retained response elements for glucocorticoids, two positionally conserved CCAAT boxes, and positionally conserved TATA boxes. The putative EBNA2 100-bp enhancers within these promoters contain 54 conserved residues, and the binding sites for CBF1 and CBF2 are well conserved. Cp usage in the HVP- and RhEBV-transformed cell lines was detected by S1 nuclease protection analysis. Transient-transfection analysis showed that promoters of both HVP and RhEBV are responsive to EBNA2 and that they bind CBF1 and CBF2 in gel mobility shift assays. These results suggest that similar mechanisms for regulation of latent gene expression are conserved among the EBV-related lymphocryptoviruses found in nonhuman primates.

In vitro and in vivo activities of oligodeoxynucleotide-based thrombin inhibitors containing neutral formacetal linkages

A series of 15-mer oligodeoxynucleotide analogues were synthesized, and their thrombin inhibitory activities in vitro and in vivo were evaluated. These oligodeoxynucleotide analogues share the same sequence (GGTTGGTGTGGTTGG) but have one or more phosphodiester linkages replaced by a neutral formacetal group. The results obtained from monosubstitutions show that no single phosphodiester group is critical for the thrombin inhibitory activity, suggesting that the interaction between the oligodeoxynucleotide and thrombin is based on a multiple-site charge-charge interaction. Analysis of the effects of different phosphodiester replacements indicates that the backside and left side of the chairlike structure formed by the molecule may be involved in binding with thrombin, presumably by having direct contacts with the anion-binding exosite of the enzyme. For the oligodeoxynucleotides containing two noncontiguous formacetal groups, the effect of the disubstitution is the sum of the effects obtained from the corresponding two monosubstitutions. Infusion of an oligodeoxynucleotide containing four formacetal groups into monkeys showed an increased in vivo anticoagulant effect and an extended in vivo half-life compared to the unmodified oligodeoxynucleotide.

Profile of status epilepticus : a prospective study

Forty adult patients (age> 14 years) of generalised convulsive status epilepticus were studied prospectively. All the patients were subjected to detailed history, neurological examination and baseline investigations including haemogram and metabolicprofile. CT scan was carried out in 26 patients. All the patients were treated with intravenous diazepam and phenytoin. The age range of the patients was 14-71 years with a mean of 32.75 ? 15.78. There were 24 males and 16 females. Twenty six patients had generalised tonic clonic seizures while 14 had partial seizures with secondary generalisation. Symptomatic epilepsy was the commonest type of epilepsy and was seen in 25 patients. The diagnosis of cryptogenic and idiopathic epilepsies was made in 11 and 4 patients respectively. Drug withdrawl precipitated status epilepticus in 5 patients and systemic infection in one. The mean frequency of seizures was 4.70??1.83/hour, mean duration was 1.78???l.0l/minutes and cumulative convulsive time 25.27??21.50 minutes. Twelve patients had focal neurologic deficits. Papilloedema was seen in four cases only. CT scan was abnormal in 18 of 26 patients. All patients except one showed immediate response to therapy. Seven patients had recurrence of seizures after initial response to diazepam and phenytoin. Low serum level of the drug at 12 hours had a significant correlation with recurrence of seizures. Ataxia was the most common side effect of phenytoin therapy. Serious side effects e.g. hypotension and respiratory depression were seen in 4 and 2 patients respectively. Two patients expired during 48 hours follow up.

Biexponential decomposition of a neuraminidase inhibitor prodrug (GS-4104) in aqueous solution

PURPOSE

To examine the degradation kinetics and identify the degradation products of a neuraminidase inhibitor prodrug. GS-4104.

METHODS

Degradation was studied as a function of pH and temperature using a stability-indicating RP-HPLC assay. Degradation products were isolated by RP-HPLC and identified by NMR. Specific rate constants were calculated based on a scheme defined by products(s) analysis.

RESULTS

Three distinct degradation products were observed in the pH region studied (pH 2-8): isomer I, GS-4071, and isomer II. Isomer I resulted from the N, N-migration of the acetyl group. Gs-4071 was formed by the hydrolysis of the ethyl ester. Both GS-4071 and isomer I degraded further to isomer II by N, N-acyl migration and ester hydrolysis, respectively. The N, N-acyl migration reaction was characterized using two dimensional heteronuclear multiple bond correlation (HMBC) NMR. The decomposition kinetics of GS-4104 follow a biexponential decay at pH 2-7. The degradation kinetics of Gs-4104 at pH 4.0, 70 degree C were independent of the initial GS-4104 concentration.

CONCLUSIONS

The degradation profile indicates that development of solution or solid dosage from of GS-4104 with adequate shelf-life stability at room temperature is feasible.

Regulation of cellular genes in a chromosomal context by the retinoblastoma tumor suppressor protein

The retinoblastoma tumor suppressor gene product (pRb) is involved in controlling cell cycle progression from G1 into S. pRb functions, in part, by regulating the activities of several transcription factors, making pRb involved in the transcriptional control of cellular genes. Transient-transfection assays have implicated pRb in the transcription of several genes, including c-fos, the interleukin-6 gene, c-myc, cdc-2, c-neu, and the transforming growth factor beta2 gene. However, these assays place the promoter in an artificial context and exclude the effects of far 5' upstream regions and chromosomal architecture on gene transcription. In these experiments, we have studied the role of pRb in the control of cell cycle-related genes within a chromosomal context and within the context of the G1 phase of the cell cycle. We have used adenovirus vectors to overexpress pRb in human osteosarcoma cells and breast cells synchronized in early G1. By RNase protection assays, we have assayed the effects of this virus-produced pRb on gene expression in these cells. These results indicate that pRb is involved in the transcriptional downregulation of the E2F-1, E2F-2, dihydrofolate reductase, thymidine kinase, c-myc, proliferating-cell nuclear antigen, p107, and p21/Cip1 genes. However, it has no effect on the transcription of the E2F-3, E2F-4, E2F-5, DP-1, DP-2, or p16/Ink4 genes. The results are consistent with the notion that pRb controls the transcription of genes involved in S-phase promotion. They also suggest that pRb negatively regulates the transcription of two of the transcription factors whose activity it also represses, E2F-1 and E2F-2, and that it plays a role in downregulating the immediate-early gene response to serum stimulation.